Copolymers of alpha-olefins and SO.sub.2 are well known in the art. These polymers may be prepared by various processes, including bulk, solution and emulsion polymerization. These copolymers have various uses, especially as thickeners for crude oil, coatings and viscosity index improvers. Copolymers of SO.sub.2 and higher alpha olefins are also well known. For example, see U.S. Pat. No. 3,409,548 which describes the use of polysulfone copolymers (in oil based, fracturing fluids, i.e. SO.sub.2 copolymerized with an alpha olefin having from 8 to 42 carbon atoms). The compositions taught in this reference differ from the instant compositions, since a fracturing fluid must be a liquid to be useful. Thus, the amount of oil combined with the polysulfone copolymer is sufficient to dissolve the copolymer in the oil. In the instant composition the oil and copolymer ratio is adjusted so that the oil is dissolved in the polymer to yield flexible materials. The instant compositions, of course, are not useful as fracturing fluids, and indeed have uses not contemplated by the patentees, e.g., as coatings.
A paper by Crawford and Gray (J. Appl. Polymer Sci. 15, 1881 (1971)) teaches copolymers of alpha olefins and sulfur dioxide and suggests that the use of longer chain olefins would result in brittle copolymers due to the crystallization of the longer chains. The materials thus suggested would be brittle and of limited use in preparing coatings, etc. To obtain flexible materials, the same authors in German Application No. 2,308,415 suggest copolymerization of a low-carbon-number olefin along with a higher olefin to effect plasticization of the copolymer. Thus, the reference suggests the polymerization of at least three different monomers to prepare the useful flexible olefin-SO.sub.2 copolymers.
U.S. Pat. No. 3,728,185 teaches compositions comprising a pyrolyzable olefin SO.sub.2 -polymer and an extender which can have from 20 to 50 wt. % of a plasticizer incorporated into the polymer. The composition has a finely divided fusible or sinterable inorganic material incorporated therein. The oil plasticizers of the instant invention have a significantly higher solubility parameter and a lower molecular weight than the polyisobutylene plasticizers of U.S. Pat. No. 3,728,185 thereby making the plasticizers of the instant invention more readily compatible with the polymers. Additionally, U.S. Pat. No. 3,728,185 does not teach the plasticization of a rigid and brittle copolymer having more than twenty carbon atoms to obtain a flexible composition. The copolymers of Gray (e.g. 1-hexadecene) are flexible to begin with as clearly seen at column 4, line 24 whereas the instant invention teaches the use of olefins with at least 20 carbon atoms to obtain copolymers having improved strengths.
U.S. Pat. No. 3,409,548 teaches SO.sub.2 -olefin copolymers which are useful as a fracturing fluid. These compositions are liquids and not solids as taught by the instant invention. The copolymer is dissolved in oil whereas in the instant application the oil is dissolved in the copolymer. Additionally, the copolymers of U.S. Pat. No. 3,409,548 are covalently crosslinked, whereas the copolymers of the present invention are completely soluble and gel free.
In the instant invention, the necessity of including a low carbon number olefin is eliminated since a broad range of hydrocarbon oils has been unexpectedly found to plasticize the copolymer to yield flexible compositions. Thus, the difficulties of polymerizing an additional monomer are avoided. It is noted that nowhere in the above reference is it taught, shown or suggested that hydrocarbon oils can be used to convert brittle copolymers of SO.sub.2 and higher alpha olefins into flexible materials.